My original post about it using the same levels was kinda unnaccurate.... Once you get a little further you see only the first part of level 1 is same the same as the Turrican 2 level 1. The rest seems to be new levels with a mix of Turrican 1 & 2 themes. Only now the levels HUGE (and the 1UP's are a little sparse).
(Also you might notice that we can no longer destroy the first exit sign which directs you into the waterfall )

I think Ash has the right approach. Turrican should never die, but some new approaches once in a while can be refreshing to see...... and since it has the original music its gotta be worth playing just to hear that again